docs: correct the example link on detox.md (#30)

Author: aurium

plugins/detox.md

@@ -70,7 +70,7 @@ If things go well, you should to have this set up:
 - An `e2e/` folder in your project root
 - An `e2e/config.json` file; [example](https://github.com/wix/Detox/blob/master/examples/demo-react-native-jest/e2e/config.json)
 - An `e2e/environment.js` file; [example](https://github.com/wix/Detox/blob/master/examples/demo-react-native-jest/e2e/environment.js)
-- An `e2e/firstTest.e2e.js` file with content similar to [this](https://github.com/wix/Detox/blob/master/examples/demo-react-native-jest/e2e/app-hello.e2e.js).
+- An `e2e/firstTest.e2e.js` file with content similar to [this](https://github.com/wix/Detox/blob/master/examples/demo-react-native-jest/e2e/app-hello.e2e.ts).
 
 There should also be a file called `.detoxrc.json` in your project root.